Stuck Ferrule (female end) question

On Jul 5, 4:12*am, riverman wrote:
On Jul 5, 12:01*pm, rw wrote:





On 7/4/10 9:38 PM, george9219 wrote:

On Jul 4, 1:02 pm, *wrote:
On 7/4/10 10:41 AM, riverman wrote:

However, the female end is less clear. Think of a donut (as the female
end of a ferrule resembles a donut in cross-section): first instincts
may say to heat the female end to expand it, but when a donut expands,
the hole actually gets smaller. SO heating the female end may make the
ferrule tighter.

I'm afraid that you're wrong. Heating the female ferrule will cause the
hole to expand. So it's best to heat the female ferrule and cool the
male ferrule.

--
Cut "to the chase" for my email address.

What RW said. Heat the female ferrule. The wall section of the female
has less mass and will expand faster than the male section.

The donut analogy is misleading. A cooking donut doesn't expand like a
"normal" material undergoing classic thermal expansion. A better analogy
is that the cross section of the ferrule would expand like a
photographic enlargement, in all directions, hole and all. That's why
mechanics sometimes use a torch to free a stuck nut. (I wouldn't use a
torch on a ferrule, but I'd use a XC ski waxing iron, carefully. You're
in Sweden, right?)

In any case, I wouldn't hold much hope for the thermal method of getting
the ferrules apart, although it's worth a try. Brute force is the
answer, I think, and if you aren't strong enough you need to find a way
to get mechanical advantage (or more hands to help).

BTW, riverman, is this a real problem you're facing or is it a quiz
question?

--
Cut "to the chase" for my email address.

It's mostly a quiz question, generated at the end of a string of
musings while casting. I dipped my travel rod in the icy water while
fishing, then noticed a short while later that the ferrule had
loosened, maybe (or maybe not) because of the immersion. So I jammed
the ferrules tightly together, however, when I tried to disassemble
the rod later, it was jammed. Although I was able to get the sections
apart using the 'behind the knee' method, I wondered about the role of
cold water immersion, and the effect on the seated ferrules and when
the rod warmed up. So I started thinking about what role hot or cold
water would have on each section.

The male section is easy....it should contract with cold water, even
if just a little. But the question began nagging me about the action
of the female section. Specifically, would cold water expand or
decrease the radius of the hole, and if it decreased it, would it
decrease less then the decrease of the male section (effectively
loosening the ferrules).

I'm not convinced that heat expands the radius of the hole, as in a
photographic enlargement. Objects expand around their physical mass.
There is a classic physics demonstration with a steel ring and a steel
ball where you heat the ring and find that the ball will not fit
through the ring. So, just as the hole in a rising donut (or bagel is
more like it) gets smaller, I would expect the hole to get smaller if
you heated the female section. But countereffecting that would be that
the circumference of the torus would also increase. Maybe there is
some sort of ratio of circumference to torus thickness where the hole
actually does not change....I don't know. But the action of the female
end of a ferrule is a very thought-provoking thing.

--riverman- Hide quoted text -

- Show quoted text -

Things do exapand like a photographic enlargement. Been there done
than and measured it.
One thing we have not considered is that the male and female ferrules
are made of different material. Rod blanks are made in one piece and
then cut into sections. Male ferrules are part of the blank and
female furrules are laid up on the exterior of the blank. The two
materials while they are the "same" could have different coefficients
of thermal expansion. The expoxy, resins and fiber used to make the
female ferrule could be different than those used to make the blank.
That could explain what you experienced in very cold water.